The invention relates to a belt retractor for a seat belt system comprising a belt tensioner and a spring cassette. The invention further relates to two alternative methods of fitting such belt retractor.
Belt retractors usually have a spring cassette including a helical spring that fulfills the functions of a close contact of the belt in the case of a belted vehicle occupant and of automatic belt webbing feed-in after the vehicle occupant has unfastened the seat belt. When the belt retractor also includes a belt tensioner, the spring cassette is usually outwardly attached, as a separate unit, to the belt tensioner which in turn is laterally disposed at the belt retractor. An example of such design is illustrated in EP 0 709 266 A1.
From EP 1 285 827 A1 a belt retractor comprising a retractor frame and a load limiter is known, the latter including an unlocking element to be actuated by a pyrotechnic actuator for releasing a locking pawl. The actuator is embedded in a casing disposed at the retractor frame. A spring cassette is integrally connected to this casing, in particular by an adhesive or by welding.